1. Technical Field of the Invention
The present invention relates to starters for use in starting up internal combustion engines of vehicles and, more particularly, to an intermediate geared starter having an intermediate gear, held in meshing engagement with a pinion gear at all times, which is moved into meshing engagement with a ring gear of an engine for startup thereof.
2. Related Art
In general, an internal combustion engine of a vehicle is started up by a starter that is supplied with electric power from an on-vehicle battery for rotation. As one type of the starter, an intermediate geared starter is known. FIG. 1 shows an example of the intermediate geared starter of the related art.
As shown in FIG. 1, the intermediate geared starter is comprised of a pinion shaft 110 carrying thereon a pinion gear 100, an intermediate shaft 120 disposed in parallel to the pinion shaft 110, and an intermediate gear 130 carried on the intermediate shaft and held in meshing engagement with the pinion gear 100 at all times. Upon movements of both the intermediate gear 130 and the pinion gear 100 in an axial direction to cause the intermediate gear 130 to be brought into meshing engagement with the ring gear 140 of the engine, a rotational force is transferred from the pinion gear 100 to the ring gear 140 via the intermediate gear 130 to start up the engine.
However, the intermediate shaft 120 is inserted and assembled to a through-bore 160 formed in a nose portion 150 of a housing to allow the through-bore 160 to support one end of the intermediate shaft 120. With such a structure, the intermediate shaft 120 is fitted to the through-bore 120 with a clearance. That is, since the through-bore 160 has an inner diameter slightly greater than an outer diameter of the intermediate shaft 120 to a degree enabling the intermediate shaft 120 to be inserted, a sliding clearance is created between the one end of the intermediate shaft 120 and the through-bore 160. Therefore, foreign materials, such as dust, enter the sliding clearance from an area (at a rightward area in FIG. 9) outside the nose portion 150 and as the foreign materials reach the intermediate gear 130 to an area between the intermediate shaft 120 and the intermediate gear 130, there is a fear of inability for the intermediate gear 130 to smoothly move on the intermediate shaft 120.